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  <title>Document</title>
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<body>
  <script>
    var str1 = 'aaa';
    var str2 = new String('aaa')
    console.log(str1.toUpperCase(),str2.toUpperCase());

    var day = new Date();
    console.log(day.getFullYear());
    var month = day.getMonth() + 1;
    console.log(month);
    // console.log(day);

    // 取[1-10]之间的整数
    var n = Math.random()
    console.log(Math.floor(n * 10 + 1));

    var n1 = '111abc';
    console.log(Number(n1));// => (NAN)Not A Number
  </script>
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